This invention relates to improvements in and concerning a machine for the manufacture of paper tubes by diagonally rolling a paper tape. More particularly this invention relates to a paper tube making machine having the productivity thereof improved by vertically disposing belts serving to roll paper tape thereby saving floor space for the installation of the machine and, at the same time, causing a plurality of rolling belts and a plurality of fixed shafs as paper tape rolling shafts to be disposed parallel.
In addition to the paper tube making machines proposed by the inventor in Japanese Patent Publications No. 17568/1977, No. 529/1978, and No. 2208/1978, many paper tube making machines have been known to the art. All these conventional machines share a construction wherein pulleys are raised with vertical shafts at the opposite ends of a horizontal arm plate disposed diagonally below a fixed shaft and an endless rolling belt wound diagonally one complete turn around the fixed shaft is passed round the two pulleys and stretched taut. In this construction, however, the arm plate protrudes considerably from the left and right lateral sides of the machine frame. When the machine is to be installed adjacent to a wall in a work shop, for example, the end of the arm plate protruding from the machine frame prevents the machine from being brought any further toward the wall. Thus, the installation of this machine calls for a large wasteful space just for the accommodation of the protruding arm plate. Besides, when a large number of produced paper tubes are to be bundled up and carried away such as on a forklift, for example, the forklift operator is required to take care to avoid collision of the forklift against the protruding arm plate. Moreover, since the conventional machine uses just one fixed shaft per machine, desired enhancement of the efficiency of paper tube production has had no alternative but to rely on an increase in the operating speed of the rolling belt. The operating speed of the rolling belt, however, is limited by the quality of paper tape used for the production of paper tubes and the type of paste used for bonding the rolled paper tape. When the rolling belt is operated at a speed exceeding the limit, the pasted portion of the freshly produced paper tube comes apart after the paper tube has passed the rolling zone relative to the fixed shaft of the rolling belt. Thus, the product has to be rejected. The rolling belt, accordingly, is operated at the highest possible speed. Despite the precaution, rejectable products occur to a fair extent. There is a further problem that bearings and other frictional parts as well as the rolling belt undergo heavy wear and require frequent replacement.
Alternatively, two horizontal arm plates are disposed below the fixed shaft in the shape of the letter X as proposed by the inventor's Japanese Patent Publication No. 17568/1977, or such two horizontal arm plates are disposed either independently or connectedly in the shape of the letter V as suggested by the conventional methods and touched upon in the patent publication mentioned above by way of reference to the prior art. Between the pulleys disposed at the opposite ends of each of the arm plates, two rolling belts are stretched taut with the directions of their inclinations reversed to each other. When the two belts are diagonally wound around the static shaft in the opposite directions to each other, the direction of the static shaft can be corrected and straightened out in the horizontal direction by relatively adjusting the tensions of the two rolling belts. The core cutting shaft which is projected extendedly from the leading end of the fixed shaft is generally supported in position on the opposed peripheral surfaces of two parallel support rollers disposed adjacently to each other. If the fixed shaft is capable of being corrected in the horizontal direction by the relative adjustment of the two belts, it does not necessarily follow that the fixed shaft will be effectively pressed against the opposed peripheral surfaces of the two support rollers. Although the core cutting shaft is supported in position on the opposed peripheral surfaces of the two support rollers, it is susceptible to considerable bouncing while the machine is in operation, with the result that the pasted portion of the freshly produced paper tube slides out of position and loses adhesive strength. Thus, there is a possibility of the paper tube being produced not in a straight form as desired but in a warped form.